Control device



Aug. 30, 1960 Q HAJNY' 2,951,189

CONTROL DEVICE Filed Nov 15, 1956 2 Sheets-Sheet 1 i5 INVENTOR.

' C zar-les E. )Z'gjn Aug. 30, 1960 c E HAJNY 2,951,189

CONTROL DEVICE Filed Nov. 13,- 1956 2 Sheets-Sheet 2 INVENTOR. 82Charles E.

my QM United States Patent CONTROL DEVICE Charles E. Hajny, Milwaukee,Wis., assignor to lSaso Inc., Milwaukee, Wis., a corporation ofWisconsin Filed Nov. 13, 1956, Ser. No. 621,703

6 Claims. (Cl. 317156) This invention relates in general toelectromagnetic control devices and more particularly to electromagneticdevices, for example, fluid fuel valves, requiring a high initial orstarting torque.

One of the main objects of the present invention is to provide animproved form of electromagnetic control device wherein the operatingforce obtained is at a maximum at the beginning of the operatingmovement, as distinguished from devices in which the force exertedinitially is a minimum. This is advantageous, particularly in a valve orswitch operator, since it provides a large initial or starting force toovercome the inertia and friction of moving parts and also toovercomethe strong initial resistance to valve opening movement caused by fluidpressures tending to hold the valve closed or spring biasing tending tohold the switch closed.

Another object is to provide a device of the aforementioned characterwhich is quiet andefiicient in operation and which affords increasedefficiency in the transformation from electrical to mechanical energy,for example, in providing for a given sized valve unit substantiallyincreased capacity as compared to known devices of similar character.

Another and more specific object of this invention is to provide adevice of the aforementioned characteristics having means therein forincreasing the starting torque of an already normally high startingtorque type electromagnetic device without a corresponding increase inthe size of the device and without an increase in the heat lossesthereof.

Another object of the invention is to provide a device as characterizedhaving therein an electromagnetic operator comprising coil means, rotormeans associated with said coil means for movement upon energization ofthe coil means and means associated with the rotor means for changingthe number of effective turns in the coil means to provide both a highstarting torque and a low running-power loss.

Another object of the invention is to provide the abovedescribed devicewith means associated with the rotor means to change the number of turnsin the winding means in response to movement of the rotor means from afirst to a second position, thereby providing a high starting torque andreducing the power required by the device when the rotor is in itssecond position and high torque is no longer needed.

Anotherspecific object of the invention is to provide a device of theclass described having two windings initially energized by line powerand opposing each other to produce high torque actuation of the rotor,and having means for disconnecting one of said windings from said sourceand short circuiting said winding to permit induction of a currenttherein for continuation of flux flow in said core means and rotor tomaintain the latter in actuated position.

Another specific object of the invention is to provide anelectromagnetic device wherein the power unit takes the form of acurrent limiting step-down transformer ice having a primary windingenergizable by line power, and a low-voltage secondary winding includingcondition responsive means or other apparatus for controlling said unit,the low voltage of said secondary winding making it unnecessary toprovide the secondary circuit with the type of insulation and theconduits required for line voltage.

A further object of the invention is to provide a device of the abovegeneral type that is sturdy and easily constructed and is otherwise welladapted for the purposes for which it is designed.

The novel features which are characteristic of the invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and its method of operation,together with additional objects and advantages thereof, will thus bebetter understood by the following description of the specificembodiments when read in connection with the accompanying drawings, inwhich:

Figure 1 is an axial sectional view of one form of the device embodyingthe present invention showing in schematic form thermostatic means forcontrolling the secondary circuit thereof;

Figure 2 is a schematic plan view of the device depicted in Figure 1showing the rotor armature in retracted relation;

Figure 3 is a view similar to Figure 2 showing the armature in attractedrelation;

Figure 4 is a schematic plan view of a modified form of the invention; I

Figure 5 is a perspective view of a rotor armature of the type used inthe devices depicted in Figures 1 to 3; and

Figure 6 is an enlarged fractional sectional plan view taken through thecontact ring of the rotor shown in Figures 1, 2 and 5 and indicating thecooperation of the fixed contacts with said contact ring when the rotoris in retracted position.

Referring to the drawings, and more particularly to Figure 1 thereof,the control selected for illustration comprises an electromagneticallyoperated valve which is of the general type or class shown in thecopending application of Floyd J. Bydalek and Russell B. Matthews,Serial No. 270,666, filed February 8, 1952, now Patent No. 2,833,565,and as shown in the issued patent of Eugene E. Meusy, No. 2,756,370,dated July 24, 1956. It is to be understood that While the invention isshown and described as an improved form of a particular type or class ofelectromagnetic device as aforementioned, the invention is not solimited in its application and its apphcability to other electromagneticdevices will become apparent.

The details of the electromagnetic device shown in Figure 1 may beascertained by referring to the aforementioned copending application andpatent.

For properly setting forth sufficient background to readily understandthe present invention, however, it should be pointed out that theillustrated form of control apparatus comprises a valve body 10 havingan inlet 11 and outlet 12. A valve member 13 cooperates with a valveseat 14 to control the flow of fluid through the valve body. It will benoted that the pressure of the controlled fluid tends to hold valvemember 13 closed agamst seat 14.

The valve body 10 has an opening 15 covered by control casing 16 ofnon-magnetic material for housing an electromagnetic power unit oroperator to be hereinafter described. The bottom wall 16a of the casing16 affords a base plate for the power unit and a plate-like cover foropening 15, said wall being sealingly secured by suitable means (notshown) to the body 10. The upper side of base plate 16a is provided witha pair of integrally 3, formed upstanding arms 16b which form a partialenclosure for a rotor or rotary armature 17 hereinafter described.

A core 19 of laminated, or of any other suitable form is disposed withincasing 16 and may be formed of any suitable magnetically permeablematerial such as iron. The particular core 19 selected for illustrationis of generally rectangular configuration, and comprises a pair ofparallel side legs 20 and 21 which are magnetically connected byparallel end legs 22 and 23 as best shown in Figures 2 and 3. The coreside legs 2%; and 21 have spaced pole pieces 24 and 25 formed, forexample, as integral parts of the core laminations, said pole pieceshaving the configuration shown in Figures 2 and 3 including arcuate polefaces defining with arms 16b of the base plate 16a, a well including anair gap in which the rotor 17 is adapted to turn.

The rotor 17 is of magnetic material, such as steel, and is of the formbest illustrated in the perspective view of Figure 5. In general therotor 17 is of solid form and is fixedly mounted on a shaft 31 which ispositioned for turning movement and is provided with suitable bearings.The illustrated bearings include balls 26 and a sleeve 27 carried by andprojecting through the cover 16a, and also include a spring loadedball-type thrust bearing 28.

As shown in Figlre l, the rotor shaft 31 extends downwardly through thesleeve 27 for connection with a crank member 40. A resilient ring 41surrounds shaft 31 within the sleeve 27 to provide a gas-tight sealtherebetween. The crank member is formed with an off-center pin 43 whichis adapted to engage a yoke or spool member 44 connected at one end, asby a stem 45, to valve member 13.

The aforementioned yoke and valve member may be suspended in the valvebody by a pair of spiral springs 47 which are fixedly attached to aportion 160 of the base plate 16a. The springs 47 serve both to supportthe valve member .13 assembly in alignment with the valve seat GM and tobias the rotor 17 and valve member 13 in a valve closing direction aswill hereinafter become apparent.

Referring back to the power unit of the device, the electrical systemcomprises a primary winding 33 which is wound on coil leg 23. Theprimary winding 33 is adapted to be connected to a suitable source 60 ofA.-C. line power by conductors 56 and 57 through circuitry which will bedescribed hereinafter. A secondary coil or winding 34 is wound aroundthe coil leg 22 and the circuit thereof includes condition responsivemeans such as a thermostat illustrated schematically at 38 in Figures 1,and 2 and 3 for opening and closing said circuit.

Devices having the general structure thus far described are shown anddescribed in the aforementioned copending application and patent. Theoperation of the instant device is, however, substantially improved overthat of prior art devices by virtue of additional structural featuresand modifications which will now be described.

As shown in Figure 2, the primary winding 33 may be provided with endtaps 33b and 330 and with a tap 33a intermediate its length. For sake ofconvenience in reference, the portion of winding 33 between end tap 33cand tap 3301 which, of course, is less than total number of turns ofsaid winding is referred to as winding portion 33d. The center tap 33ais connected by a suitable conductor 54 to a fixed contact 51, the endtap 33b is connected to a fixed contact 52 by conductor 55, and the endtap 33c is connected to conductor 57 which is also connected to one sideof the source 60. The other side of source 60 is connected to a fixedcontact 50 by a suitable conductor 56.

Means for alternatively connecting the entire winding 33 or the portion33d thereof across the source 6! is provided by suitable contact meanssuch as a contact sleeve 32 (Figures Sand 6) which is carried by therotor 17 and cooperable with the contacts 50, 5'1 and 52. Theelectrically conductive contact sleeve 32 may be molded into aninsulating bushing 31a fixedly mounted on the rotor stem 31 and ispreferably formed with side wall openings 32c and 32d separated by wallportions 320 and 32b. Wall portion 32b is continuously engaged bycontact 50, and wall portion 32d is positioned for engagement by thecontact 51 as shown in Figures 2 and 6 when the rotor 17 is in retractedposition, to complete the circuit between contacts 50 and 51. Onrotation of the rotor to the attracted position of Figure 2, the wallportion 32d of sleeve 32 moves out of engagement with contact 51 andinto engagement with contact 52 to thereby complete the circuit betweencontacts 50 and 52.

From the aforedescribed circuitry, it is apparent that when the rotor isin the retracted position shown in Figures 2 and 6, only portion 33d ofwinding 33 is energized as follows: from source 60, through conductor56, contact 50, sleeve 32, contact 51, conductor 54, tap 33a, portion33d of coil 33, end tap 33c, and conductor 57 back to source 60. On theother hand, when the rotor is in the attracted position shown in Figure3 of the drawings, the entire coil or winding 33 is energized throughthe following circuitry: from source 60, through conductor 56, contact50, sleeve 32, contact 52, conductor 55, end tap 33b, entire coil '33,end tap 33c, and conductor 57 back to source 60.

The operation of the improved device shown in Figures 2, 3 and 6 willnow be described. With the parts of the device disposed as shown inFigures 2 and 6, the portion 33d of winding 33 is energized to create amagnetic flux in the core 19 that flows, during one half of thealternation current cycle, in a clockwise direction and during the otherhalf cycle in the opposite direction through side leg 20, end leg 22,side leg 21 and leg 23. The majority of this flux tends to flow throughleg 22 of core 19 only so long as the circuit of the secondary winding34 remains open.

When the thermostat '38 calls for heat, the contacts thereof close thecircuit of the secondary winding 34 and a current is thereupon inducedinto said winding. A major portion of the magnetic flux in the core 1 9will now no longer flow through end leg 22, but will be diverted acrossthe air gap afforded by the pole pieces 24 and 25. The flux flowingacross the air gap tends to rotate the rotor from its retracted positionof Figure 2 to its attracted position of Figure 3 with a very highstarting torque which is effective to open the valve 14 against fluidpressure and against the bias of springs 47. It is to be understood thatthe torque thus developed is susbtantial- 1y higher than that developedin other devices of the same class due to the fact that less than thetotal number of turns in winding 33 are energized to effect suchmovement.

The improved starting torque is obtained for the following reasons: Theimpedance oifered by the less than total number of turns in portion 33dof the winding is less than the impedance offered by the total winding33 (the latter being substantially the same as the primary windings indevices heretofore except for the intermediate tap 33a). Thus, when aload is impressed on the portion 33d of the primary winding by theclosure of the secondary circuit, a relative and abnormally high amountof current will flow in said winding portion as compared with amountthat would fiow if the entire winding 33 were energized. This currentflow produces a very high Ni and consequently a high magnetic flux whichis shunted through the poles 24- 25 and rotor 17. Since flux crosses anair gap at the point of minimum air gap, and since the minimum air gapoccurs at the point where the leading edges of the rotor 17 arepresented to the pole pieces, the magnetic flux is concentrated at thosepoints, imparting a very high counter-clockwise torque to the rotor 17.

Extremely high starting torque is thus occasioned both by theconcentration of magnetic'flux into a limited area of rotor and poleface surface presented to each other and by the large amount of magneticflux available due to the increased NI occasioned by energization ofonly a portion of the total number of turns in the primary winding 33.

The inherent tendency of the device is to tend toward a condition ofminimum effective air gap. Hence, the rotor '17 will be rotated into theair gap until the arms 17a and 17b thereof are in substantial registrywith the pole faces 24 and 25 respectively to define the attractedposition of said 'rotor shown in Figure 3. Further counterclockwiserotation of the rotor =17 will not occur since suchmovement would tendto increase the air gap, setting up magnetic forces creating a torque inthe opposite direction. The rotor 17 is thereby afforded a magnetic stoplimiting its rotation in counterclockwise direction.

If the aforementioned abnormally high current is permitted to continueflowing through the winding portion 33d, as distinguished, from theentire winding 33, the primary would soon overheat. The improved deviceis, however, constructed in a manner to prevent such overheating,.therebeing means operable upon partial opening of the valve 13 to cause theentire Winding 33 to be energiZBd. This reduces the NI produced in theprimary winding as well as the heat generated therein, and it alsoreduces the armature torque. Since there is need for the high armaturetorque only during initial cracking of the valve 13, however, thereduced armature torque available after partial opening of said valve isadequate for movement of said valve to its full open position. Theaforementioned change in the number of energized turns of the winding 33is effected by movement of the wall portion 32a of contact sleeve 32 outof engagement with contact 51 and into engagement with contact 52 uponrotation of the contact sleeve 32 with the rotor 17 toward the attractedposition of the latter.

The reason for the reduced heat losses and NI produced by theenergization of the entire winding 33 shall now be explained. Ifarbitrarily the center tap 33a is disposed at the midpoint of thewinding 33, then when the turns. are doubled by movement of the rotorcontact sleeve 32, the primary impedance more than doubles. This obtainsbecause the reactance part of the primary impedanceis a function of thesquare of the number of turns of said winding. Since the primary turnsare doubled and the primary current goes to less than half of theinitial current because of the impedance change, the effective NIavailable at the pole faces 24 and 25 decreases to correspondinglyreduce the armature torque.

The reduction in. heat losses is obtained because heat losses are afunction of PR, and although the resistance of the primary doubles bydoubling the turns thereof, the current flow drops to less than half dueto the additional effect of the impedance change aforenoted. Thus, thePR heat losses occurring when the entire winding 33 is energized areless than one half of the heat losses occurringwhen only one half of thewinding is energized.

Another factor that affects the amount of current flow in the primarywinding 33, and hence the NI, is the change in reluctance in themagnetic path due to the change in the air gap. Inasmuch as thereluctance is high, initially due to. the very small amount of rotorarea presented to the pole faces, a low impedance is obtained in theprimary which permits a very high initial current flow affording. a highstarting torque. The aforementioned reluctance becomes lower as therotor presents more and more area to the pole faces, and the currentflow, therefore, drops correspondingly. Thus it is observed that thedevice will have an extremely low operating loss because of both thedecrease in reluctance in the magnetic path and the increase in thenumber of energizedturns in the winding resulting in a lower currentflow.

It is, of course, understood that the rotation of the rotor 17 andconsequent movement of the valve member 13 through the linkage of shaft31, crank member 40 and yoke 44 is against the bias of springs 47 whichreturn both the valve member 13 and the rotor 17 to their initialpositions upon cessation of flux flow across the air gap between polefaces 24 and 25 effected, for example, by reopening of the thermostat38. It should further be noted that such return will be prompt andwithout dangerous sticking, since the rotor 17 never seals against thepole faces 24 and 25; that is, the air gap therebetween, althoughminimized by registration of the rotor arm to the pole pieces, is nevercompletely eliminated and said minimum air gap remains constantthroughout the life of the device. The device is not, therefore, subjectto residual magnetism of the core 19, the differential of the flux valuerequired to pull in the rotor, and that at which it will drop out isthereby greatly minimized, rendering the control extremely sensitive andfast-acting.

Another desirable feature of the aforedescribed device is that it isinherently more efficient than known electromagnetic operators as, forexample, the power requirement is about one-sixth that of a conventionalsolenoid operator, and substantially less than that of the devices ofthe same class disclosed in the aforementioned patent and copendingapplication.

Figure 4 is a View similar to Figure 2 and showing a modified form ofthe invention. It is to be understood that Figure 4 is a schematicpresentation of a device of the same general type shown in Figure l. Theprimed numerals in Figure 4 indicate parts which are similar to theparts indicated in the other figures by the same numerals unprirned. Itis to be noted that the thermostat 38' is located in the primary windingcircuit and affords a complete shut off of power to said winding whenthe circuit is broken at said thermostat. As shown, the secondarywinding 34' is connected in parallel circuit with the primary winding 33through normally closed con tacts 70 and 71, whereby upon closure ofthermostat contacts, both coils become energized directly from source60' in such a manner that the magnetic flux generated by one of saidwindings tends to flow in the core side legs 20' and 21' in a directionopposite to the direction in which the flux generated by the otherwinding tends to flow in said side legs. As a result, flux is shuntedacross the air gap defined by the pole faces 24' and 25', producing ahigh counterclockwise torque in the armature 17'. A cam of insulatingmaterial is fixed on rotor stem 31' and rotates with the rotor 17' toengage contact leaves 70 and 71 and disengage the latter from each otherto open the circuit between conductors 82 and 84 leading to source 60'.Cam 90 simultaneously causes contact 71 to engage a contact '72 toafford, through contacts 71 and 72 and conductors 82 and 83, a shortcircuit for the portion of winding 34 between the terminal thereofconnected to conductor 82 and a suitable tap 75 (which may be placedanywhere along its length as desired) to which the conductor 83 isconnected. The coil 34' is now a shorted secondary which operates in amanner similar to that of the coil 34 in the other figures, i.e., thecurrent induced therein maintaining the flux created by the primary 33'diverted across the air gap to maintain the rotor in attracted positionand the valve open.

The structure shown in Figure 4 also affords high starting torque and avery low running power requirement. The device depicted in Figure 4 isalso particularly adaptable to a multiple valve application wherein itis desired to have a single thermostat control several valvessimultaneously.

Although certain specific embodiments of the invention have been shownand described, it is with full awareness that many modifications thereofare possible within the inventive concept.

The invention, therefore, is not to "7 be restricted except insofar asis necessitated by the prior art and by the appended claims.

What is claimed by the invention is: V.

1. An electromagnetic device comprising a permeable core having an airgap, a rotor having its axis of rotation within said air gap, magneticflux source means comprising first and second windings for producing amagnetic flux in said core and through said air gap, said rotor beingrotatable from a first to a second position in response to said fluxflow in said air gap, a control member operatively associated with'saidrotor for actuation thereby and requiring"a first force to initiatemovement from a first controlling position and a second force tocontinue said movement once initiated toward a second controllingposition, means associated with said rotor and said mag netic fluxsource means comprising contact means normally connecting said windingsin parallel circuit relation and actuated by the rotor to interrupt saidconnection and short circuit at least a portion of said secondaryWinding to thereby afford a first amount of flux in said air gap whensaid control member is in its first controlling position and thereforerequires said first force for movement thereof and affording a secondamount of flux in said air gap for continuing movement of saidcontrol'member once movement thereof toward said second controllingposition is initiated.

2. An electromagnetic device comprising a permeable core having an airgap, a rotor having its axis of rotation within said air gap, magneticsource means comprising a primary and a secondary winding for producinga magnetic flux in said core and through said air gap, said rotor beingrotatable from a first to a second position in response to said fluxflow in said air gap, a control member operatively associated with saidrotor for actuation thereby and requiring a first force to initiatemovement from a first controlling position and a second force tocontinue said movement once initiated toward a second controllingposition, means associated with said rotor and said magnetic flux sourcemeans comprising contact means in circuit with the primary winding andactuated by the rotor for changing the number of effective turns thereinto vary the inductive reactance and hence the flux produced thereby toaiford a first amount of flux in said air gap when. said control memberis in its first controlling position and therefore requires said firstforce for moveprimary and a secondary winding for producing a magneticflux in said core and through said air gap, said rotor being rotatablefrom a first to a second position in response to said flux flow in saidair gap, a control member operatively associated with said rotor foractuation thereby and requiring a first force to initiate movement froma first controlling position and a second force to continue saidmovement once initiated toward a second controlling position, meansassociated with said rotor and said magnetic flux source meanscomprising contact means in circuit with said secondary winding andactuated by the rotor to change the number of effective turns therein tovary the inductive reactance and hence the flux produced thereby toafford a first amount of flux in said air gap when said control memberis in its first controlling position and therefore requires said firstforce for movement thereof and to afford a second amount of flux in saidair gap for continuing movement of said control member once movementthereof toward said second controlling position is initiated.

4. An electromagnetic operator comprising a permeable core affording aclosed magnetic circuit and also having pole pieces defining an air gap,magnetic flux source means comprising a primary and a secondary windingon said core for producing a magnetic flux in said core, first andsecond control means for varying the amount of flux at said pole pieces,said first control means being connected to a source of electricalenergy and to both of said windings and operable upon actuation thereofto effect energization of both of said windings and initiate flux flowthrough said air gap, a rotor having its axis of rotation in said airgap having surfaces adapted to be drawn into said air gap by said fluxflow therethrough, said second control means being connected in circuitwith both of said windings, and said rotor being associated with saidsecond control means for actuation thereof to disconnect said secondarywinding from said source: of electric energy and short circuit a portionof said winding, whereby actuation of said first control means initiatessufficient rotary motion to said rotor with maximum force at thebeginning of its movement to satisfy the inherent tendency of said fluxto minimize the air gap through which it is forced to flow, and furthermovement of said rotor aifords actuations of said second control meansto afford a reduction in the flux flow through said air gap.

5. An electromagnetic operator comprising a magnetically permeable corehaving an air gap, an armature mounted for movement in said air gap andadapted for connection to a control member to be actuated, magnetic fluxsource means comprising first and second windings for producing magneticflux in said core and through said air gap, said armature being movablefrom a first to a second position in response to fiux flow in said airgap, means associated with said armature and said magnetic flux sourcemeans comprising contact means connecting said windings in parallelcircuit relation when saidartnature is in its first position andactuated by movement of said armature toward its second position tointerrupt said connection and short circuit at least a portion of saidsecondary winding to thereby afford a first amount of flux in said airgap when said armature is in its first position and a second smalleramount of flux in said air gap when said armature is in its secondposition.

6. An electromagnetic operator comprising a magnetically permeable coreaffording a closed magnetic circuit and also having pole pieces definingan air gap, magnetic flux source means comprising a primary and asecondary winding on said core for producing opposing magnetic fluxflows in said core and thereby flux flow across said air gap, first andsecond control means for varying the amount of flux in said air gap,said first con trol means being connected to a source of electricalenergy and to both of said windings and operable upon actuation thereofto effect energization of both of said windings and initiate flux flowthrough said air gap at a first rate, an armature movable from a firsttoward a second position by flux flow through said air gap, said secondcontrolmeans being connected in circuit with both windings, and saidrotor being associated with said second control means for actuationthereof to disconnect said secondary winding from said source ofelectric energy and short circuit at least a portion of said winding,whereby actuation of said first control means initiates motion of saidarmature from its first toward its second position, and such movement ofsaid armature affords actuation of said second control means to afford areduction in the flux flow through said air gap.

References Cited in the file of this patent UNITED STATES PATENTS954,745 Larsen Apr. 12, 1910 2,115,748 Reisner May 3, 1938 2,344,178Sparrow Mar. 14, 1944 2,687,870 Matthews Aug. 31, 1954 2,756,370 .MeusyJuly 24, 1956

